Exemestane + Celecoxib vs Exemestane + Placebo in Metastatic Breast Cancer

Inclusion Criteria: * Femal patient aged \> 18 years * Histologically proven breast cancer * Menopausal patient according to the following definition: * amenorrhoea \> 1 year or menopause affirmed by a rate of oestradiol or hypophyseal gonadotrophin * surgical ovariectomy * treatment by LHRH analog * ovarian suppression by radiotherapy * amenorrhoea induced by chemotherapy \> 1 year * Oestradiol and/or progesterone positive receptors * Presence of one or several metastatic lesion: * mesurable lesion * bone metastase were detected by bone scintigraphy * Patient who can have received: * Adjuvant chemotherapy and/or hormonotherapy (Tamoxifen) * Metastatic Treatment by chemotherapy * PS \< 2 * Adequate biological values * Patient who has clearly given her consent by signing on informed consent form prior to participation Exclusion Criteria: * Patient previously treated with hormonotherapy in metastatic phase * Antecedent of treatment with aromatase inhibitors * local relapse (with the exception of cutaneous thoracic nodes) * Patient with only one metastatic lesion like: pleurisy , ascites, lung Lymphangitis carcinomatosa